SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9958d056da5d67514d038556b251297a8bef17499c3ebeb7822bece19c9e6a47' 
  AND token = '9US43cyQSbbCqJYyAMlQMf4yPPvTEoOt3JgtDLr8PsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}